Method and apparatus for completing wells



Jan, 21, 1941. L. R. cRQFT rAL METHOD AND APPARATUS FOR COMPLETING WELLS Filed Jan. 1l, 1940 Patented Jan. 21, 1941 UNTED STATES METHGD AND APPARATUS FOR COMPLETING WELLS Leland R. Croft and Clyde S. Sanders, Tulsa,

Okla., assignors to Stanolind Oil and Gas Company, Tulsa, Okla., a corporation of Delaware Application January 11, 1940, Serial No. 313,391

D Y 16 Claims. This invention relates to a method and apparatus for drilling and especially for completing wells and more particularly to a method and apparatus for completing oil wells.

Oil andgas wells are commonly drilled by the rotary method using drilling mud for the purposes of cooling and lubricating the bit, mudding olf porous strata above the producing horizon and carrying the cuttings to the surface. however, often undesirable to utilize drilling mud when completing a well, i. e. when drilling into the formation from which it is desired to produce oil or gas. It is well known that permeable formations carrying water offer a very high resistance to the flow of oil, 'I'he use of drilling mud in a well produces a region adjacent the Well bore which is saturated with mud or water, which region tends to dam ofi the ow of oil to the well. For this reason wells have sometimes been completed by drilling them in the normal method with mud to a point above the pay horizonand then utilizing oil as the drilling iiuid while drilling into the producing stratum. In most cases oil is thus used in connection with a pressure drilling technique in order to provide sufficient pressure to overcome the hydrostatic pressure of the producing formation and in connection with reverse circulation, i. e. circulation up through the tubing or drill pipes instead of down through it, in order to improve the carrying powers of the oil for the cuttings in view of the higher velocity in the tubing than in the annular space surrounding it. This type of circulation also serves to remove the cuttings from the well without allowing them to come in contact with the face of the pay horizon or with the liner and packer assembly, so that these cannot be mudded up.

However, when this technique is used for completing a well in a poorly consolidated formation, it is necessary after the hole has been drilled into the producing horizon to pullthe vdrill string, and then insert and set a tubing screen or strainer in the hole. Since all of this must be done under pressure, itis diflicult as well as a time-consuming operation. Moreover, if it is subsequently desired to drill the hole still deeper the tubing with its associated strainer must be pulled from the hole and the drilling apparatus must again be inserted. After redrillng the tubing and strainer must again be inserted and set.

It is an object of the invention to provide a method and apparatus whereby the nnal drilling operation and the setting of the strainer can be It iS,'

(Cl. Z55- 1) vide a method of and apparatus for drilling into anv o il producing horizon without leaving Water in theoil sand, and maintaining the walls in good condition bykeeping the drilling apparatus in the well during the whole completion operation.

A still further object of the invention is to provide a method and apparatus whereby a wellican be tested eciently at various `depths of penetration to determine oil and gas productivity without removing the drilling apparatus from the well. A still further object of the invention is to provide methods and apparatus whereby a well can be electrically logged in the producing formation and whereby the well can then be completed in the desired producing formation without danger of forming a mud sheath on the face of the producing formation. These and other advantages, uses and objects of the invention will become readily apparent as the description of the invention proceeds.

One method oi utilizing this invention is toA drill a small sized hole commonly known as a rat hole, through the producing stratum, or through a stratum which it is desired to test to determine its productivity. Having drilled such a -rat hole. the pay sand is electrically logged or otherwise tested by the use of various types of apparatus known to the art which can be run into the rat hole in order to determine the characteristics of this stratum or its productivity. Having determined by means of electrical logging or otherwise that this producing stratum is the one from which it is desired to produce, the casing can then be set above this stratum and cemented at the desired depth in the usual manner. After drilling the cement plug the apparatus described herein is then run in the well on the tubing string and the small diameter hole is reamed to a larger size, thereby removing the mud sheath formed in drilling the rat hole. While drilling the full sized hole the liner assem- :bly including a strainer is carried into the hole behind the bit during the drilling operation. When this `operation ls completed the strainer is set, as will hereinafter appear, and the well is ready for production without removing the drilling apparatus.

It will be apparent that the apparatus of this invention can also be used for drilling through the cement plug if so desired and it will also be apparent that the apparatus to be described is of considerable utility even if the small hole is not drilled into the producing horizon rst. lin other words, if a. given horizon is known to be the one from which it is desired to produce, the conventional drilling operation using drilling mud can be discontinued immediately above the producing horizon or soon after entering it and the apparatus of this invention can be used for the completion operation. In fact it is even possible @a to utilize the apparatus of this invention for drilling at higher levels or throughout the entire drilling operation.

Also while it is preferred in accordance with this invention to complete wells by the use of oil as the drilling fluid and to use the reverse method of circulation to remove the cuttings from the well, it will be apparent that both4 the method andthe apparatus of this invention can be utilized to advantage using other drilling uids, including drilling muds, and using normal instead of reverse circulation.

The invention will be more fully described with reference to the accompanying drawing in which:

Figure 1 is a sectional elevation of the upper portion of the apparatus;

Figure 2 is an elevation partly in section of the lower portion of the apparatus, the upper part of Figure 2 being joined to the lower part of Figure 1 to make the complete apparatus; and

Figure 3 corresponds to Figure 1 and shows the apparatus in condition for production rather than in condition for drilling as in the case of Figure 1.

VAfter running the assembly shown in Figures 1 and 2 into the well on the .tubing or drill pipe preparatory to drilling into the producing horizon, the conventional Christmas tree and blowout preventer are installed, after which the apparatus of the present invention is lowered to the top of the small diameter hole previously referred to or to any other point at which it is desired to commence the use of this apparatus, and a tubing hanger is then installed on the top of the tubing. Following thisfthe kelly is secured in the tubing hanger, the blow-out preventer is closed and the well is reamed or drilled to the desired depth by the use of the apparatus of this invention. Since the apparatus referred to at the upper part of the well is old in the art and forms ,no part of this invention, it is not shown in the drawing and is referred to merely -to describe more fully the method of utilizing the apparatus.

The apparatus shown in the drawing has as its principal parts an upper bearing A, a packer B together with equipment for seating and unseating it, a liner and screen assembly C, a releasing tool and valve assembly D, a lower bearing assembly E, and a bit F; In drilling into the pro- 1 ducing formation the drill bit F is rotated by the tubing II, which is used as a drill pipe, through special sections of tubing or drill pipes I2 and I3 which are connected by releasing tool and valve assembly D. Drill pipe I3 is preferably Welded to releasing tool D, and to the bit F. During this drilling the liner and screen assembly C including outer packer sleeve I4, blank casing I5, screen or strainer 16, blank casing II and plug I8 remain stationary or relatively so due to friction with the walls of the hole and due to the action of bearing A and bearing assembly E. Thus the fractional resistance of the drilling operation is kept low and the casing screen is notl subjected to wear and plugging during the drilling operation.

During this drilling operation the preferred procedure is to circulate oil around the outside of the apparatus then up Vthrough ports IB to bit F, tubing or drill pipe sections I3 and I2 and tubing or drill pipe II to the conventional surface apparatus.

Following the drilling operation pipe section I2 is unscrewed from releasing tool O by turning the drill pipe or tubing II and I2 to the left from the surface and raising the tubing toV the position shown in Figure 3. When pipe section I2 is unscrewed and raised, backA pressure valve 20 is closed by action of spring 2| as shown in Figure 3 and the production from the well must therefore necessarily pass through slots 22 in screen I6 and thence up through special tubing section I2 rather than through ports I9 to bit F. The slots 22 in the screen or strainer I6 may be of any desired shape 'and construction. They may, for example, be ,vertically or horizontally cut narrow slots, or larger holes covered witha wire wrapping. after the tubing has been raised as shown in Figure 3, packer B is set by means o'f a setting tool, hereinafter referred to, and the tubing can then be raised still further and suspended on -the Christmas tree in the usual manner. joint is then backed out and raised above the master gate valve in the Christmas tree, the valve is closed and the drilling operation is completed with the well ready to produce.

` After setting the packer and testing production.

the packer can be unset/and the well can be drilled deeper. For instance, after productivity has declinedthe packer can be unset and the well can be drilled to a deeper pay horizon without removing the apparatus from the well.

The apparatus will now be described in somewhat more detail to make clear the action of the various parts.

'I'he upper bearing A, which serves to connect the bottom standl of tubing I I and special tubing section I2, and which is equipped ,with grooves 23 for fluid packing, is tted suiliciently closely to the innerv packer sleeve 24 as to direct the iiow of drilling fluid around the outside of the packer collar 25.

Packer B is preferably made of an oil resistance rubber-like composition such as Neoprene or Thiokol rather than the conventional canvas wrapping so that the packer may be reset several times without pulling it from the well.

It will be noted that the upper end of packer B is connected to collar 25 which iheld in fixed position with respect to inner packer sleeve 24 by weld 26. 'I'he lower end of packer B isconnected to outer packer sleeve Il. Collar 25 can be moved translationally with respect to theV outer packer sleeve I4, within certain limits Between these two packer sleeves aresprings 21 which are located in grooves 28 out in the outer part of the inner packer sleeve. 'I'hese springs serve to hold the two sleeves in constant relative position to each other except when the packer is operated. The two packer sleeves are additionally restrained from rotating with respect to each other by means of pins 29 operating in slots 30 in the outer sleeve. These pins also limit`the vertical motion of the inner packer sleeve 24 with respect to the outer packer sleeve To the lower end of the outer packer sleeve Il is connected blank casing I5 which is shown broken and which can be of any desired length. This blank casing is in turn connected to the screen or strainer I6 to which reference has previously been made, and which can be of any desired length. 'I'his is in turn connected to a second section of blank casing I? which is in turn connected to plug i3.

Returning to special tubing section l2 it will be seen that this carries two Z shaped ribs 3i located opposite each other below the bottom of the inner packer sleeve 2d when the latter is connected with tool D. The rib actually shown is on the back of the pipe and is therefore shown in dotted lines. As'will become4 apparent, the two ribs are so arranged that they have a similar locking action. 'Ihese ribs 3l are designed to cooperate with lugs 32 which are spaced 180 apart on the lower end of inner packer sleeve 24.

To set the packer B the combination drill pipe and tubing string il carrying with it the upper tubing section i2 is turned slowly to the left hrto disengage releasing tool D and is raised until the bottom steps 33 of Z tools 3i are above lugs 32. While still turning to the left the drill pipe il is then lowered until the bottom steps of the Z tools engage with the lugs 32 and lowering is then continued except'that inner sleeve 2t is now forced down along with tubing section i2. Collar 2li is likewise brought downward, thus expanding packer B against the walls ofthe casing 34 (Figure 3). At the bottom of this casing is casing shoe 35. The packer being thus set and held in position by springs 2l, the tubing can be still further raised to the position shown in Figure 3 and suspended in the Christmas tree as previously described. The wellv can now be produced.

Should it be desired to release the packer B for any reason, this can be done by lowering the tubing iI while turning it to the right untilthe upper steps 36 of the Z tools 3i have passed below lugs 32. 'Ihen while continuing the righthand rotation the tubing is raised engaging the upper steps 35 with lugs 32 and raising inner packer sleeve 24 along with collar 25, thus releasing the packer tc its unsetv position. The upward travel of the inner sleeve is, of course, controlled by pins 2 9 which travel in slots 30.

'Ihe pressure exerted by springs 2'! between sleeves 24 and I4 must be suilicient to overcome the upward force exerted by the expanding packa This special tubing section'when in drilling position extends into a sleeve portion 31 of releasing tool D, ending near shoulder 38 (Figure l). In a recessed portion of sleeve portion 31 is back pressure valve 20 actuated by spring 2l as previously described. In Figure 1 this` back pressure valve is shown in its open position while in Figure 3 it is` shown in closed position. It will be apparent, of course, that the upper shoulder 39 at the top of sleeve portion 31 is correspondingly shaped to provide a seat for valve 20.

The lower end of releasing tool D is threaded to receive the upper end of lower special tubing section I3. Between this lower tubing section and. blank casing II of liner assembly C is disposed lower bearing assembly E which includes radial bearing 40, thrust bearing 4I. and radial and thrust bearing I2. These bearings are associated with supporting members located on special tubing section I3 and on blank casing II. Since the function and nature of these will be apparent from the drawing they will not be described in detail.

To prevent the entry of cuttings, sand, etc. into the bearings, upper and lower packing glands A3 are provided. These packing glands each include collars 44 and i5, the latter collars being carried by collars 45 welded to blank casing il. Collars 46 serve a dual function in connection with both the packing glands and the bearings MJ and 42.

Packing glands d3 together with tubing section I3 and blank casing i'i define a compartment which is preferably packed with oil or grease so that bau bearings am, in and t2 .wm operate efciently 'and the drill pipe including special tubing sections I2 and i3 will be free to rotate without turning the liner assembly C.

At the bottom of special tubing section i3 is a bit F which has been mentioned previously. The bit shown is of the fish tail type but diners from the usual iish tail bit in that ports i9 are placed near the edges of cutting blades (Il, which are two or more in number, so that the cuttings are forced into the streams of fluid entering ports I9. The distance from the ports to the cutting edges of the blades is not greater than the greatest dimension of the ports. These ports are shown as oblong and as offering as much opening along the blade of the bit as can be provided without unduly weakening it. However, the area of each port should preferably not be greater than one-half of the cross sectional area of the drill pipe, and may preferably be substantially less, since this increases the iiuid velocity at this point and serves to prevent any clogging of the port.

While the invention has been described in connection with a specific embodiment thereof, it is to be understood that this is by.way of illustration and not by way of restriction and that the invention is not ylimitedto the specific details shown but only to the subject matter of the appended claims.

We claim: f

l. A method of completing-a well comprising drilling into a producing formation, lowering a Well screen into said producing formation during said drilling operation, setting said well screen, and producing from said formation through said screen.

2. A method of completing a well comprising drilling into a producing formation to form a hole larger than a wellscreen, lowering said Well screen into said producing formation during said drilling operation, setting a packer above said well screen, and producing from said formation through said screen.

3. A method of completing a well comprising drilling a small hole into a producing formation, testing said producing formation by means of said small hole, reaming said hole in said producing formation to a larger diameter, lowering a well screen into said producing formation during said reaniing operation, setting said well screen, and producing from said formation through said screen.

4. A method according to claim 3 in which said second-mentioned drilling operation is conducted using oil as the drilling fluid.

5. A method according to claim 3 in which said second-mentioned drilling operation is' conducted using reverse circulation with oil as the drilling uid.

6. A method of completing a well comprising drilling a small holeinto a. producing formation, testing said producing formation by means of said small hole, setting and cementing a casing above said producing formation, drilling through said i cement and into said producing formation a hole diameter less than the diameter of said lastmentioned hole into said producing formation during said drilling operation without interrupting said drilling operation, setting said well screen, and producing from said formation through said well screen.

7. Drilling apparatus comprising a drill string,

a drill bit carried by the lower end of said drill eter than the hole drilled by said drill bit, said well screen surrounding a part of said drill string, means supporting said well screen from said drill string and providing free relative rotation between said well screen and said drill string, and means whereby oil produced from the well drilled with said apparatus can be forced to pass through said well screen.

9. Drilling apparatus comprising a bltconstructed and arrangedto drill a hole, a combination drill pipe and tubing associated with said bit, a liner assembly surrounding part of said combination drill pipe and tubing, said liner assembly being of lesser diameter than said hole, and bearings located between said combination drill pipe and tubing and said liner assembly whereby said combination drill pipe and tubing can be rotated, thereby rotating. said bit, without rotating said liner assembly.

10. Drilling apparatus comprising a bit constructed and arranged to make a hole, a combination drill pipe and tubing associated with said bit, a liner assembly surrounding part of said combination drill pipe and tubing, said liner assembly being of lesser diameter than said hole,

' bearings located between said combination drill pipe and tubing and said liner assemblywhereby said combination drill pipe and tubing can be rotated, thereby rotating said bit, without rotating said liner assembly, said liner assembly comprising a screen. and a packer located above sai screen. A 11. Apparatus for" completing a well comprising a drill bit, a combination drill pipe and tubing associated with said drill bit, a linerv assembly associated with the lower part of said combination drill pipe and tubing, said liner assembly having a diameter less than ,thai diameter of the hole drilled by said drill bit, bearings to permit rotation of said combination drill pipe and tubing without the rotation of said liner assembly, means for disconnecting two sections of said combination drill pipe and tubing, and valve means associated with said last-mentioned means.

l2. Apparatus for completing a well comprising a drill bit equipped with pots for the passage of drilling fluid, a combination drill pipe and tubing. associated with said drill bit fand communicating with said ports during drilling, a liner assembly including a well screen associated with the lower part of said combinationdrill pipe and tubing, said liner assembly having a diameter less than the diameter of the hole drilled by said drill bit, 4bearings to permit rotation of Jasaaaeea said combination drill pipe and tubing without the rotation of said liner assembly,l and a check valve for disconnecting duid communication between the upper part ofgsaid combination drill pipe and tubing and said ports.

' 13. Apparatus for completing a ywell comprising a drill bit equipped with ports for the passage of drilling fluid, ia combination drill pipe and tubing associated with said drill bit and communicating with said ports during drilling, a

sections of said combination drill pipe and tubing.l

are disconnected.

. 14. Apparatus Vfor completing a well comprising a drill bit, a combination drill pipe and tub.- ing associated with said drill bit, a liner assembly associated with the lower part of said combination drill pipe and tubing, said liner assembly having a diameter less than the diameter of the hole drilled by said drill bit, bearings to permit rotation of said combination drill pipe and tubing without the rotation of said liner assembly, a packer associated with said liner assembly, means associated with said combination drill pipe and tubing for actuating said packer, means for disconnecting two sections of said combination drill pipe and tubing, and valve means associated with said last-mentioned means.

15. Apparatus for completing a well comprising a drill bit, a combination drill pipe and tubing associated with said drill bit, a liner assembly associated with the lower part of said combination drill pipe and tubing, said liner assembly having a diameter less than the diameter of p the hole drilled by said drill bit, bearings to permit rotation of said combination Ldrill pipe and tubing without the rotation of said liner assembly, a packer associated with 'said liner assembly, means associated with said combination drill pipe and tubing for actuating said packer, means including springs for frictionally preventing accidental actuation of said packer, means for disconnecting two sections of said combination drill pipe and tubing, and Valve means associated with said last-mentioned means.

16. Apparatus for completing a well by reverse circulation drilling using oil as the drilling iuid comprising a drill bit having at least two blades, 

